#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N = 5e2 + 5;
const int mod = 998244353;
void inc(int &x, int y) { x = (x + y >= mod) ? x + y - mod : x + y; }
int n, m, a[N], c[N][N];
int binom(int n, int m)
{
	if (n < 0 || m < 0 || n < m) return 0;
	return c[n][m];
}
int f[N][N];
int main()
{
	scanf("%d", &n);
	for (int i = 1; i <= n; i++) { scanf("%d", &a[i]); m += a[i]; }
	for (int i = 0; i <= m; i++)
	{
		c[i][0] = 1;
		for (int j = 1; j <= i; j++) c[i][j] = (c[i - 1][j] + c[i - 1][j - 1]) % mod;
	}
	for (int i = 2, sum = a[1]; i <= n; sum += a[i], i++)
	{
		if (!a[i]) { for (int j = 1; j <= m; j++) f[i][j] = f[i - 1][j]; }
		else
		for (int j = 1; j < sum + a[i]; j++)
		{
			if (sum) inc(f[i][j], binom(sum - j + a[i], a[i] - 1));
			for (int k = 1; k <= j; k++) inc(f[i][j], (LL) f[i - 1][k] * binom(sum - j + a[i], a[i] - 1) % mod);
		}
	}
	int ans = 1;
	for (int i = 1; i < m; i++) inc(ans, f[n][i]);
	printf("%d\n", ans);
	return 0;
}